Showing papers by "John Chiefari published in 1999"
TL;DR: In this article, the nonbonded electron pair of the nitrogen included as part of an aromatic system was used as an additive component for living radical polymerization with reversible addition−fragmentation chain transfer.
Abstract: Living radical polymerization with reversible addition−fragmentation chain transfer (RAFT polymerization) can be achieved with the use of dithiocarbamate derivatives that have the nonbonded electron pair of the nitrogen included as part of an aromatic system. These compounds have been shown to be highly effective in RAFT polymerization of styrene and (meth)acrylate esters to produce polymers of predetermined molecular weight and narrow polydispersity (usually <1.2). By contrast, simple N,N-dialkyl dithiocarbamates (those compounds previously described as “photoiniferters”) are ineffective as RAFT agents. The reasons for the different behavior are discussed.
516 citations
TL;DR: In this article, the authors describe the preparation of polyacrylate and polystyrene macromonomers using the catalytic chain transfer (CCT) with cobalt complexes, which does not require the use of an added chain transfer agent or an R-methyl-substituted vinyl monomer as comonomer.
Abstract: Two effective and well-known methods for the preparation of macromonomers are the use of radical addition-fragmentation chain transfer agents (e.g., allyl sulfides)6 and catalytic chain transfer (CCT) with cobalt complexes.7-10 Recently, the scope of the CCT process has been expanded by demonstrating how cobalt complexes can be used to prepare macromonomers based on, among others, acrylates and styrene by copolymerizing these monomers in the presence of R-methylsubstituted comonomers, such as R-methylstyrene and methyl methacrylate.11 We now wish to report on a new process leading to macromonomers of structure 2 and 3 based on monosubstituted monomers which does not require the use of an added chain transfer agent or an R-methyl-substituted vinyl monomer as comonomer.12 In this communication, we describe the preparation of polyacrylate and polystyrene macromonomers using this process.
155 citations
TL;DR: The RAFT polymerization as mentioned in this paper is a method for the control of free radical polymerization and its use in the preparation of narrow polydispersity polymers of various architectures.
Abstract: SUMMARY: This paper describes a versatile and effective method for the control of free radical polymerization and its use in the preparation of narrow polydispersity polymers of various architectures. Living character is conferred to conventional free radical polymerization by the addition of a thiocarbonylthio compound of general structure S=C(Z)SR, for example, S=C(Ph)SC(CH3)2Ph. The mechanism involves Reversible AdditionFragmentation chain Transfer and, for convenience of referral, we have designated it the RAFT polymerization. The process is compatible with a very wide range of monomers including functional monomers such as acrylic acid, hydroxyethyl methacrylate, and dimethy laminoethyl methacrylate. Examples of narrow polydispersity (51.2) homopolymers, copolymers, gradient copolymers, end-functional polymers, star polymers, A-B diblock and A-B-A triblock copolymers are presented.
136 citations